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Five people died after two major earthquakes struck near Indonesia, authorities said Thursday.

Three of the people died from heart attacks while the others died of shock after two earthquakes struck Wednesday, officials with Indonesia's Disaster Mitigation Agency said.

The first massive earthquake struck off the coast of the Indonesian island of Sumatra on Wednesday afternoon, triggering a tsunami watch for the Indian Ocean, which was later canceled. It was an 8.6-magnitude quake.

The second large quake, with a magnitude of 8.2, occurred off the west coast of Sumatra about two hours later, the U.S. Geological Survey said.